How to convert intArray to ArrayList<Int> in Kotlin?

From

val array = intArrayOf(5, 3, 0, 2, 4, 1, 0, 5, 2, 3, 1, 4)

I need to convert to ArrayList<Int>

I have tried array.toTypedArray()

But it converted to Array<Int> instead

Solution 1:

You can use toCollection function and specify ArrayList as a mutable collection to fill:

val arrayList = intArrayOf(1, 2, 5).toCollection(ArrayList())

You can get List<Int> with a simple toList call like so:

val list = intArrayOf(5, 3, 0, 2).toList()

However if you really need ArrayList you can create it too:

val list = arrayListOf(*intArrayOf(5, 3, 0, 2).toTypedArray())

or using more idiomatic Kotlin API as suggested by @Ilya:

val arrayList = intArrayOf(1, 2, 5).toCollection(ArrayList())

Or if you'd like to do the above yourself and save some allocations:

val arrayList = intArrayOf(5, 3, 0, 2).let { intList ->
    ArrayList<Int>(intList.size).apply { intList.forEach { add(it) } }
}